Apparatus for measuring prevailing instantaneous tension in an elongate strand

Abstract

The prevailing tension in an elongate strand, such as a textile yarn, is instantaneously measured, even at very low levels of tension and at fine incremental changes in tension, by a tension measuring apparatus utilizing a pair of fixed contact arms spaced from one another to define a strand contact line therebetween and an intermediate cantilevered sensing arm disposed at an equal spacing from each fixed contact arm and at a lateral spacing from the stand contact line. The fixed contact arms and the sensing arm are contacted with the strand simultaneously at the same common lateral side of the strand to cause the strand to deflect from the strand contact line at equivalent strand break angles between the respective strand contact points on the fixed contact arms and on the sensing arm. An electrically powered strain gauge, preferably incorporating a Wheatstone bridge circuit, is associated with the sensing arm to generate a continuous electrical output signal varying instantaneously in proportion to the corresponding instantaneous tension prevailing in the strand while in contact with the fixed contact arms and the sensing arm. In one embodiment, the measuring apparatus is contained within a portable hand-held housing for manual placement in contact with a strand whose tension is to be measured, with an auxiliary hand-held housing supplying electrical power to the strain gauge and containing a microprocessor to compute a quantitative tension value from the output signal received from the strain gauge.

We claim: 
     
       1. Apparatus for measuring prevailing instantaneous tension in an elongate strand comprising a pair of fixed contact elements arranged at a spacing from one another, the fixed contact elements defining a strand contact line therebetween for simultaneously contacting the strand in-situ at a common lateral side thereof at respective points along the strand contact line, a sensing element supported in a deflectable cantilevered disposition intermediate the fixed contact at an equal spacing from each thereof and at a lateral spacing from the strand contact line for contacting the strand simultaneously with the fixed contact elements at a sensing point at the same common lateral side of the strand to cause the strand to deflect from the strand contact line at equivalent strand break angles between the respective strand contact points on the fixed contact elements and the sensing point on the sensing element, the sensing element having an opening laterally therethrough for reducing the force required to deflect the sensing element from a resting cantilevered position, the opening being of an ellipsoidal shape in relation to the length of the sensing element, and electrically powered strain gauge means associated with the sensing element for generating a continuous electrical output signal varying instantaneously in proportion to the corresponding instantaneous tension prevailing in the strand in contact with the fixed contact elements and the sensing element. 
     
     
       2. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 1, wherein the strain gauge means comprises a Wheatstone bridge circuit having excitation means and signal means at each of two opposite sides of the sensing element relative to a plane of deflection normal to the strand contact line for producing the electrical output signal in proportion to both strand tension increases and decreases. 
     
     
       3. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 1, further comprising a housing, the fixed contact elements, the sensing element and the strain gauge means being mounted to the housing. 
     
     
       4. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 3, wherein the housing is configured to be held in a user's hand for portability. 
     
     
       5. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 1, further comprising means for computing a quantitative tension value from the output signal of the strain gauge means. 
     
     
       6. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 5, further comprising means for displaying the tension value computed by the computing means. 
     
     
       7. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 6, wherein the computing means continuously computes the tension value instantaneously from the output signal and the display means continuously displays the instantaneously computed tension value. 
     
     
       8. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 7, further comprising an electrical power supply source connected to the strain gauge means, the computing means and the display means. 
     
     
       9. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 8, further comprising portable housing means to be carried in a user's hands from one strand tension-sensing location to another, the fixed contact elements, the sensing element, the strain gauge means, the computing means, the display means and the electrical supply source being mounted to said housing means. 
     
     
       10. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 9, wherein the housing means comprises a first portable housing to be held in one hand of a user and a second portable housing to be held in the other hand of the user, the fixed contact elements, the sensing element and the strain gauge means being mounted to the first housing and the electrical supply source, the computing means and the display means being mounted to the second housing, electrical lead means extending between the first and second housings for connecting the strain gauge means with the electrical supply source, the computing means and the display means. 
     
     
       11. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 1, wherein the fixed contact elements comprise fixed contact arms and the sensing element comprises a sensing arm. 
     
     
       12. Apparatus for measuring prevailing instantaneous tension in an elongate strand comprising a sensing arm supported in a deflectable cantilevered disposition for contacting the strand to cause the strand to deflect about the sensing arm, the sensing arm having an opening laterally therethrough for reducing the force required to deflect the sensing arm from a resting cantilevered position, the opening being of an ellipsoidal shape in relation to the length of the sensing arm, and electrically powered strain gauge means associated with the sensing arm for generating a continuous electrical output signal varying instantaneously in proportion to the corresponding instantaneous tension prevailing in the strand in contact with the sensing arm. 
     
     
       13. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 12, wherein the strain gauge means comprises a Wheatstone bridge circuit having excitation means and signal means at each of two opposite sides of the sensing arm relative to a plane of deflection normal to a line of strand contact with the sensing arm for producing the electrical output signal in proportion to both strand tension increases and decreases. 
     
     
       14. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 12, further comprising a housing, the sensing arm and the strain gauge means being mounted to the housing. 
     
     
       15. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 14, wherein the housing is configured to be held in a user's hand for portability. 
     
     
       16. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 12, further comprising means for computing a quantitative tension value from the output signal of the strain gauge means. 
     
     
       17. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 16, further comprising means for displaying the tension value computed by the computing means. 
     
     
       18. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 17, wherein the computing means continuously computes the tension value instantaneously from the output signal and the display means continuously displays the instantaneously computed tension valve. 
     
     
       19. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 18, further comprising an electrical power supply source connected to the strain gauge means, the computing means and tile display means. 
     
     
       20. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 19, further comprising portable housing means to be carried in a user's hands from one strand tension-sensing location to another, the sensing arm, the strain gauge means, the computing means, the display means and the electrical supply source being mounted to said housing means. 
     
     
       21. Apparatus for measuring prevailing instantaneous tension in an elongate strand according to claim 20, wherein the housing means comprises a first portable housing to be held in one hand of a user and a second portable housing to be held in the other hand of the user, the sensing arm and the strain gauge means being mounted to the first housing and tile electrical supply source, the computing means and the display means being mounted to the second housing, electrical lead means extending between the first and second housings for connecting the strain gauge means with the electrical supply source, the computing means and the display means. 
     
     
       22. Apparatus for measuring prevailing instantaneous tension in an elongate strand comprising a pair of fixed contact arms arranged at a spacing from one another, the fixed contact arms defining a strand contact line therebetween for simultaneously contacting the strand in-situ at a common lateral side thereof at respective points along the strand contact line, a sensing arm supported in a deflectable cantilevered disposition intermediate the fixed contact arms at an equal spacing from each thereof and at a lateral spacing from the strand contact line for contacting the strand simultaneously with the fixed contact arms at a sensing point at the same common lateral side of the strand to cause the strand to deflect from the strand contact line at equivalent strand break angles between the respective strand contact points on the fixed contact arms and the sensing point on the sensing arm, electrically powered strain gauge means associated with the sensing arm for generating a continuous electrical output: signal varying instantaneously in proportion to the corresponding instantaneous tension prevailing in the strand in contact with the fixed contact arms and the sensing arm, means for continuously computing a quantitative tension value instantaneously from the output signal of the strain gauge means, means for continuously displaying the tension value instantaneously computed by the computing means, an electrical power supply source connected to the strain gauge means, the computing means and the display means, portable housing means to be carried in a user's hands from one strand tension-sensing location to another, the housing means comprising a first portable housing to be held in one hand of a user and a second portable housing to be held in the other hand of the user, the fixed contact arms, the sensing arm and the strain gauge means being mounted to the first housing and the electrical supply source, the computing means and the display means being mounted to the second housing, and electrical lead means extending between the first and second housings for connecting the strain gauge means with the electrical supply source, the computing means and the display means.